1. Field of the Invention
The present invention relates to an image reading apparatus which reads an image of an original and an image forming apparatus provided with the image reading apparatus.
2. Description of the Related Art
Conventionally, the image forming apparatus includes the image reading apparatus in an upper portion of a main body thereof, and the original is copied on a sheet based on information on the original image read by the image reading apparatus, thereby discharging the sheet to the outside to provide the copy of the original to a user.
The image reading apparatus includes an original base plate, an original pressing portion, and an image reading portion. The original is placed on the original base plate. The original pressing portion can be opened and closed with respect to the original base plate, and the original pressing portion presses the original against an original base plate while closed. The image reading portion reads an image of the original which is pressed against the original base plate by the original pressing portion. In such cases, the original pressing portion includes an original conveying apparatus which automatically feeds the original to the original base plate and pressing plate (hereinafter referred to as “original conveying apparatus”).
In some pieces of image reading apparatus, when a user places the original on the original base plate, the original conveying apparatus or pressing plate is opened and closed by one motor (for example, see Japanese patent Application Laid-Open No. 2006-50225).
However, in the conventional image reading apparatus, a large motor having a large driving force is required because the original conveying apparatus is opened and closed by the one motor. Sometimes the use of the large motor locally needs a wide installation space to restrict the installation space of the motor.
Therefore, it has been thought that the original conveying apparatus is opened and closed by plural small motors.
In the original conveying apparatus of the image reading apparatus in which the plural motors are used, when a variation in rotation angular velocity between the motors is generated, the original conveying apparatus is inclined about a front-back direction axis (for example, the letter L1 of FIG. 3) or vibration is generated in the original conveying apparatus. Particularly, the phenomenon such as the inclination and the vibration emerges significantly in the case of an uneven weight distribution of the original conveying apparatus.
Accordingly, in the image reading apparatus in which the plural motors are used, the original conveying apparatus cannot smoothly be opened and closed, or a noise is generated. Additionally, the original is pressed against the original base plate while the original conveying apparatus is inclined, thereby shifting a position of the original.
In the image forming apparatus including the image reading apparatus in which the original position is shifted, when the image of the original is copied on the sheet, because the position of the copied image is shifted, it is necessary to perform the read of the original with the image reading apparatus and the copy of the image on the sheet again.